The Sun – Center of the Solar System
You may remember going outside on a hot summer night, laying down on the grass, and looking up to gaze at the numerous stars that speckle the night sky. Because these stars are so far away and miniscule, it’s hard to believe that our Sun, which we perceive as being so immense, is actually quite average, with only a few being significantly larger or smaller. However, despite its size, it’s apparent that the Sun is perfect the way it is, as it offers just enough heat and light in order for life to thrive on Earth.
The Sun is something that has intrigued human civilization for ages. The Egyptians worshipped the Sun god, Ra, above all other gods and believed Ra to go through an endless cycle of death and rebirth with each sunset and sunrise. In a way, the Sun is the preserver of life, as without its light, heat, and energy, the Earth would be a lifeless, black orb floating into obscurity. Through photosynthesis, plants can grow, and thus animals are able to nourish their bodies and populate the world.
Centuries ago, it was also believed that the Earth was the center of the Universe, and that all of the celestial bodies in the sky, including the Sun, revolved around it. If the Sun could speak, perhaps it would say something about how egocentric us Earthlings were! The fact is that all of the planets revolve around the Sun, not the Earth, and it accounts for approximately 98% of the mass in the entire Solar System. The Sun’s gravitational pull is also so strong that even Pluto, which is 5,900,000,000 km away, is held firmly in its orbit. And just like how the planets revolve around the Sun, the Sun also orbits around the center of the Milky Way Galaxy. This path that the Sun is on, takes 225,000,000 years to complete, traveling at a rate of 800,000 km per hour.
Great Ball of Fire!
The Sun, which is composed of hot gases and elements such as hydrogen, helium, calcium, sodium, magnesium, and iron, is a giant thermonuclear reactor that converts hydrogen to helium in its core in order to produce heat and light. The reason the Sun does not explode like a thermonuclear bomb is because the Sun is held together in an equilibrium state by the mutual gravitational attractions between all of its atoms acting to compress the solar center. As a result, this is able to contain the nuclear reactions taking place.
It does not come as a big surprise that the Sun is extremely hot. The surface of the sun is much cooler than its inner core, however, being only 5800 degrees, while the middle of the Sun is at least 10 million degrees. But the surface of the Sun is still about 16 times hotter than boiling water. The outer atmosphere of Sun, which is invisible to the eyes, the temperature escalates to about 1.5 to 2 million degrees. But not only is the Sun hot, it is extremely bright as well. Just staring in its direction practically blinds you! However, it is only the Sun’s outer surface that shines brightly, as the inside of the sun is completely black. The light or photons that are emitted from the Sun also cover a broad spectrum varying between very long wavelengths (such as radio) to very short wavelengths (such as an X-Ray).
As the sun is 93 million miles away it is sometimes hard to ascertain just how massive the sun really is. The light the sun releases takes about 8 minutes to reach the Earth’s atmosphere. As light travels at an extremely fast rate, this fact helps us realize just how far away the sun really is. Although it is not suggested that you gaze directly at the sun, from Earth’s atmosphere, the sun appears to be only tad bigger than the size of the moon. However, if Earth were placed right beside the sun (but let’s hope that never happens, or else we will literally be toast), the sun could be metaphorically compared to being the size of a basketball while the earth would be the size of a pin on a needle. And if the Sun were a hallow orb, the Earth would be able to fit inside the Sun a million times!
And A Star Was Born. . .
So how did the Sun come to be? Well, the Sun was created from a nebula like every other star. A nebula is a huge swirling cloud of gas, and within this cloud, all of the matter of our entire solar system existed. However, because the Sun makes up 98% of the solar system, the other 2% of the matter in the cloud formed all of the planets, moons, and the countless asteroids, meteors, and comets.
Right now, the Sun is almost half-way through its life and is classified as a Yellow G2 Star,’ which is an average, middle-aged star that emits a yellowish, almost white, light. As the Sun has been active for about 4.6 billion years, it is at its most stable point in its lifetime, and has enough fuel to go on for another 5 billion years. At the end of its life, the Sun will increase significantly in size and become a Red Giant, swallowing up all of the Inner Planets, including earth, and heating up the Outer Planets. After a billion years, the Sun will suddenly collapse into a white dwarf, taking a trillion years to cool off completely.
Although the thought of the entire existence of Earth is frightening to some, because the Sun’s life is far from being over, it is something that is hard for us to fathom. However, like the old saying goes: All good things must come to an end. The Sun is one of the most intriguing heavenly bodies and just as the Earth revolves around it, so does our very existence.
Resources:
http://www.hao.ucar.edu/Public/education/basic.html#what
http://www.hao.ucar.edu/Public/education/morebasic.html
http://members.aol.com/_ht_a/bobalien99/sunten.htm
http://www.solarviews.com/eng/sun.htm
